規則準直排列純鎳金屬矽化物奈米線、奈米管及異質結構陣列之製備與性質研究

Fabrication and Properties of Well-ordered Arrays of Single-crystalline NiSi2 Nanowires, Nanotubes and Epitaxial NiSi2/Si Heterostructures

莊振富(Chen-Fu Chuang)

指導教授 ： 鄭紹良

國立中央大學/工學院/化學工程與材料工程學系/博士(2014年)

摘要

本研究中在(001)矽晶基材上製備出規則準直排列的二矽化鎳(NiSi2)/矽(Si)的異質結構和純單晶二矽化鎳奈米線陣列結構。此結果指出鎳金屬在矽奈米線上進行界面矽化反應，在低溫退火300℃ 時，觀察到Epi-NiSi2之奈米結構在{1 ̅11} Si上有特定刻面形貌形成，現象從一開始到時間停止都只有唯一這反應相出現。 此外在較高溫退火500 ℃ 4小時，矽在奈米線中的剩餘部分將被完全消耗，二矽 化鎳/矽異質結構奈米線轉變成為全矽化物二矽化鎳奈米線。從穿透式電子顯微鏡(TEM)及選區電子繞射(SAED)分析中，可發現全二矽化鎳奈米線是單晶結構且它們其軸向方向是平行於[001]方向。所製備出準直排列的二矽化鎳奈米線，由於其良好有序排列的單晶結構，並且較低的有效功函數，性質呈現出非常低的啟動電場1.1 V /μm，具有優異的場發射特性。
矽化物奈米線的表面潤濕性，發現水接觸角由疏水性轉換親水性歸因於二矽化鎳相的形成，而水接觸角的角度遞減原因於矽化反應程度增加後。結果可發現全鎳矽化物奈米線最為親水，此現象可以用Wenzel model 解釋。所得到結果呈現出令人振奮的願景，這論文所提出的新方法將提供製造其高度規則有序準直完全矽化物奈米線結構陣列的能力，並可能提供潛在的應用在構建以垂直式矽化物為基底的奈米元件上。
這論文第二部份是成功利用蒸鍍鎳金屬於奈米線上，並結合熱退火與濕式蝕刻步驟在矽晶上製備出規則準直有序排列的二矽化鎳(NiSi2)奈米管狀結構，並量測其試片場發性質。

關鍵字

二矽化鎳 ； 矽化鎳 ； 奈米線 ； 奈米管 ； 場發效益 ； 潤濕特性

並列摘要

In this study, we reported the design, fabrication, and characterization of well-ordered arrays of vertically-aligned, epitaxial NiSi2/Si heterostructures and single-crystalline NiSi2 nanowires on (001)Si substrates, The epitaxial NiSi2 with {1 ̅11} facets was found to be the first and the only silicide phase formed inside the Si nanowires after annealing at a temperature as low as 300 ℃. Upon annealing at 500 ℃ for 4 h, the residual parts of Si nannwires were completely consumed and the NiSi2/Si heterostructured nanowires were transformed to fully silicided NiSi2 nanowires. TEM and SAED analyses indicated that all the NiSi2 nanowires were single crystalline and their axial orientations were parallel to the [001] directions. The obtained vertically -aligned NiSi2 nanowires, owing to their well-ordered arrangement, single-crystalline structure, and lower effective work function, exhibit supertior field-emission properties with a very low turn-on field of 1.1 V/μm. The surface wettability of the nanowires was found to turn from hydrophobic to hydrophilic after the formation of NiSi2 phase and the measured water contact angle decreased with an increase in the degree of the Ni silicidation reaction. The increased hydrophilicity could be explained by the Wenzel moder. The obtained results present the exciting prospects that the new approach proposed here would provide the capability to fabricate other highly-ordered, vertically-aligned fully silicide nanowire arrays and may offer potential application in constructing vertical silicide-based nanodevices.
An effective method was demonstrated for obtaining well-aligned NiSi2 NTs with favorable morphological features for field emission and wetting properties by combining single-step Ni evaporation with a subsequent wet etching process.

並列關鍵字

NiSi2 ； Nickel Silicide ； Nanowires ； Nanotubes ； Field emission ； wetting properties

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